How to select unique combinations from an array?

Question

PHP

I have an array, for example:

$array = array('orange', 'apple', 'banana', 'pine');

You need to get all the unique combinations from it.
That is, it should look like this:

array('orange', 'apple');
array('orange', 'banana');
array('orange', 'pine');
array('orange', 'apple', 'banana');
array('orange', 'apple',  'pine');
array('apple', 'banana');
array('apple', 'pine');
array('apple', 'banana', 'pine');
array('banana', 'pine');

Answer 1

One of the many solutions:
stackoverflow.com/questions/4279722/php-recursion-...

$a = array('orange', 'apple', 'banana', 'pine');

$len  = count($a);
$list = array();

for ($i = 1; $i < (1 << $len); $i++) {
    $c = [];
    for ($j = 0; $j < $len; $j++) {
    	if ($i & (1 << $j)) {
            $c[] = $a[$j];
    	}
    }
    $list[] = $c;
}

print_r($list);

ideone.com/YE9BII

Answer 2

Mm ... in fact, the task is reduced to building an enumeration + checking the occurrence of an element in a set.
To check, it is worth defining some function that associates an array with a certain string (in fact, some kind of hashing function), and the string will be unique for each possible array.
Then the uniqueness can be controlled by checking the unique strings of the current value that already exist in some array.

Answer 3

At first we will clean up
Then we will make a cycle in a cycle and by search for each value of an array we will substitute the others. In the process, add it to a new array. Ready.